Chemistyr Flashcards
What is the periodic table?
A list of all the known elements
What two main categories are there in the periodic table?
Metals and non metals
Group and period meaning
Group is down and period is across
Metal characteristics
high melting points.
good conductors of electricity.
good conductors of heat.
high density.
malleable.
ductile.
lustrous and shiny.
solid at room temperature except for mercury (liquid)
What happens when metals react with oxygen?
Metal + oxygen —-> metal oxide
What happens when metal reacts with water? Especially G1
Metal + Water Metal hydroxide + hydrogen
What are some group 1 metals
Lithium, sodium, and potassium
What are the group 1 metals also known as
Alkali metals
Properties of G1
are soft (they can be cut with a knife)
have relatively low
melting points
The alkali metals also have low
densities
. They are low enough for the first three (lithium, sodium and potassium) to float on water.
has a pH greater than 7 when dissolved in water
They must be stored under oil to keep air and water away from them. When they react with water, Group 1 elements form metal hydroxides which are alkaline. (with a pH above 7). This is why they are called alkali metals.
Reactivity of L,S and P when contacted with water
Lithium, Li Fizzes steadily, slowly becomes smaller until it disappears
Sodium, Na Melts to form a ball, fizzes rapidly, quickly becomes smaller until it disappears
Potassium, K Quickly melts to form a ball, burns violently with sparks and a lilac flame, disappears rapidly, often with a small explosion
Reactivity trend in G1 metal as you descend
As you go down the group the reactivity is greater. This is because they are metals and they loose an electron when they react. The further away the electrons are from the nucleus, the easier it is to loose one as the force of attraction decreases.
How do you test for hydrogen with a lit splint?
holding a burning splint near to the top of the test tube for the squeaky pop test.
What are group 2 metals called
Alkaline earth metals
What happens when strontium, calcium and magnesium are added to water
These all react with cold water with increasing vigour to give the metal hydroxide and hydrogen. Strontium and barium have reactivities similar to lithium in Group 1 of the Periodic Table.
Calcium, for example, reacts fairly vigorously with cold water in an exothermic reaction. Bubbles of hydrogen gas are given off, and a white precipitate (of calcium hydroxide) is formed, together with an alkaline solution (also of calcium hydroxide - calcium hydroxide is slightly soluble).
Very clean magnesium ribbon has a very slight reaction with cold water. After several minutes, some bubbles of hydrogen form on its surface, and the coil of magnesium ribbon usually floats to the surface. However, the reaction soon stops because the magnesium hydroxide formed is almost insoluble in water and forms a barrier on the magnesium preventing further reaction.
Trend of reactivity in AEM
Same as G1 metals
Describe the relative reactivity of the Alkaline Earth metals compared to the Alkali metals
Less reactive
What are the group 7 metals also known as
Halogens
Chlorine
Yellow - green gas
Use : disinfect water
Fluorine
Yellow - green gas
Use : creating nuclear material for nuclear power plants
Bromine
Red / brown liquid
Use : agricultural chemicals
Iodine
Grey solid
Use : printing inks
What is a diatomic molecule
Molecules composed of one two atoms
Chlorine reaction to iron wool
Burning, sparks, flame producing an orange gas. Iron goes yellow. Orange gas = iron chloride
